Damien Parent – Moriond, February PSR J , PSR J , and their cousins -- young & noisy gamma ray pulsars Damien Parent on behalf of the Fermi LAT Collaboration

Damien Parent – Moriond, February The context Before the launch of the Fermi Gamma-ray Space Telescope in 2008 June, we built a list of gamma-ray pulsar candidates based on their spin-down energy Edot. It seemed gamma-ray emitting electron-positron cascades occur for Edot > 3 x erg s -1 (Thompson et al. 1999). We have selected pulsars with Edot > 1 x erg s -1. These pulsars are mainly young, energetic and exhibit rotational instabilities (« timing noise »). Extract from the list of gamma-ray pulsar candidates (Smith et al. 2008)

Damien Parent – Moriond, February Discovery of pulsations from PSR J in SNR 3C 58 with Fermi Supernova remnant 3C 58. Optical(green), GHz radio (red). Fesen et al. (2008)

Damien Parent – Moriond, February PSR J , the X-ray discovery in the SNR 3C 58 X-ray Observations This young pulsar was discovered at X-ray wavelengths by the Chandra X-ray Observatory with a pulsation period of 65.7 ms (Murray et al. 2002). RXTE data allowed a measurement of the spin-down rate of Pdot = 1.93 x s s -1. The pulsed fraction for the folded light curve is ~ 21%. The pulsar has a spin-down energy Edot = 2.7 x erg s -1 (the third most energetic of the known Galactic pulsars). Edot = 4  ² I Pdot/P 3 (I: moment of inertia) 3C 58 Possible remnant of historical supernova SN 1181, in disagreement with the characteristic age  (=P/2Pdot) of the pulsar (5400 yrs) Similar to the comparably aged Crab nebula (a flat- spectrum radio nebula, non-thermal extended X-ray emission, point-like emission due to a pulsar) but differs both in luminosity and in size. Distance of ~ 3.2 kpc (Roberts et al. 1993)... suspected by Becker et al. in Image of 3C 58 at 1.4 GHz. The arrow marks the position of the pulsar. Pulsar Phase X-ray

Damien Parent – Moriond, February PSR J , the radio observations Radio observations The radio discovery was made possible by the Chandra X-ray discovery (Camilo et al. 2002) Observed with a real weak signal of ~0.045 mJy at 1400 MHz One sharp pulse of width 2 ms The distance determined from the dispersion measures of ~141 cm -3 pc is 4.5 kpc. Timing irregularities Extremely high level of timing noise Two glitches have occured since its discovery « Giant » glitch comparable to the glitches from the older Vela pulsar. Pulse profile of PSR J displayed as a function of time(bottom) and summed (top). Data at a center frequency of 1375 MHz.

Damien Parent – Moriond, February Background PRELIMINARY PSR J , the  -ray light curve   -radio = 0.07   = 0.49 The profile is very similar of the Vela light curve: with a radio delay ~ 0.1 cycles a separation of the cycles of the  -ray peaks FWHM(P1)= / cycles FWHM(P2)= / cycles An evidence for an excess between P1 and P2 appears with a significance of ~ 6 . Unpulsed emission defined between in phase consistent with the background estimated from regions around the source. 9.0 x cm -2 s -1 95% CL upper limit on unpulsed emission (PWN). Abdo et al. (2009) in preparation

Damien Parent – Moriond, February PSR J , the light curves as a function of the energy P1/P2 ratio decreases with energy No significant change in gamma peak position and shape Similar behavior as for Vela, Crab, Geminga and B The highest energy photon is in P2 with an energy of 4 GeV. P1/P2 = / P1/P2 = / P1/P2 = / PRELIMINARY

Damien Parent – Moriond, February PSR J , the spectral energy distribution The young pulsars like Crab or B have the maximum luminosity below 30 MeV. Lx/L  larger than for older pulsars. We analysed the spectrum with a standard analysis tool for the collaboration « gtlike 1 » The  -ray spectral analysis suggests an index  of 1.97 ± 0.26 with an exponential (b = 1) cut-off Ec = 2.2 ± 1.1 GeV. (1) PRELIMINARY

Damien Parent – Moriond, February Fermi LAT detection of pulsed  -rays from the Vela-like pulsar J Radio pulse profile of PSR J at 1412 MHz (Discovery, Halpern et al. 2001).... Halpern et al. (2001) report the detection of radio and X-ray pulsations in the error box of the EGRET source 3EG J  0FGL J (see Jean Ballet’s talk)

Damien Parent – Moriond, February J , the radio observation Radio parameters Pulsations at a period of 51.6 ms, Pdot ~ 7.8 x s s -1 Edot = 2.2 x erg s -1 (the fourth most energetic of the known Galactic pulsars) Characteristic age of ~ 10,500 yrs Surface magnetic flux density B ~ 2e+12 G The distance determined from the dispersion measures of ~200 cm -3 pc is ~ 7 kpc. Pulse profile The radio profile consists of one peak with FWHM of 0.08 ± 0.02 cycles. Radio pulse profile of PSR J at 1412 MHz. The phase-averaged flux density is only ~ 0.25 mJy.

Damien Parent – Moriond, February J , the X-ray observation Association Associated with SNR G (shell morphology with an extremely flat radio spectrum) Distance of ~ 3 kpc estimated from the X-ray absorption X-ray profile The pulsed fraction for the X-ray folded light curve is ~ 75%. X-ray pulse profile of PSR J in the keV band from the ASCA GIS. A portion of the Chandra ACIS-I image showing PSR J and its associated PWN (greyscale) called the Boomerang PWN. The NVSS 20 cm map of the partial shell G is overlaid (contours).

Damien Parent – Moriond, February PRELIMINARY PSR J , the  -ray light curve The  -ray profile consists of a single, asymmetric peak. FWHM(Peak)= 0.17 ± 0.03 cycles   -radio = 0.49+/- 0.01

Damien Parent – Moriond, February PSR J , the light curves as a function of the energy Evolution of the peak as a function of the energy Peak position is not stable  GeV -> 0.5 +/  GeV -> /  GeV ->0.45 +/  > 3.0 GeV -> / No significant change in gamma peak shape with energy The highest energy photon is observed with an energy of ~ 13.5 GeV in the peak. PRELIMINARY Abdo et al. (2009) in preparation

Damien Parent – Moriond, February Their cousins PSR J , this talk PSR J , this talk PSR J , Kerr’s talk MSP pulsars, Guillemot’s talk Vela, Razzano’s talk J , Caliandro’s talk Blind search pulsars, Giordano’s talk Crab, Grondin’s talk

Damien Parent – Moriond, February Summary The Fermi LAT Telescope has discovered two young pulsars in the Galactic plane, PSR J and PSR J and presents a new opportunity to study pulsar / PWN associations at high energies. The gamma-ray light curve for PSR J consists of two peaks for which the first peak trails the radio pulse by 0.07 and its amplitude decreases with increasing energy as for the known gamma-ray pulsars like Vela, Crab and Geminga. The Vela-like (comparable age) pulsar PSR J consists of one peak for which the location is variable as a function of the energy. Our gamma-ray pulsar candidates are becoming gamma-ray pulsar discoveries. We see what we expected (and more !). Our selection based on Edot isn’t so bad !